# Header Parameters { #header-parameters }

You can define Header parameters the same way you define `Query`, `Path` and `Cookie` parameters.

## Import `Header` { #import-header }

First import `Header`:

{* ../../docs_src/header_params/tutorial001_an_py310.py hl[3] *}

## Declare `Header` parameters { #declare-header-parameters }

Then declare the header parameters using the same structure as with `Path`, `Query` and `Cookie`.

# Header Parameter Models { #header-parameter-models }

If you have a group of related **header parameters**, you can create a **Pydantic model** to declare them.

This would allow you to **re-use the model** in **multiple places** and also to declare validations and metadata for all the parameters at once. 😎

/// note

This is supported since FastAPI version `0.115.0`. 🤓

///

	}
}

var isHTTPHeaderSizeTooLargeTests = []struct {
	header     http.Header
	shouldFail bool
}{
	{header: generateHeader(0, 0), shouldFail: false},
	{header: generateHeader(1024, 0), shouldFail: false},
	{header: generateHeader(2048, 0), shouldFail: false},
	{header: generateHeader(8*1024+1, 0), shouldFail: true},
	{header: generateHeader(0, 1024), shouldFail: false},
	{header: generateHeader(0, 2048), shouldFail: true},

	defer func(flag bool) { globalIsTLS = flag }(globalIsTLS)
	globalIsTLS = true
	for i, test := range encryptRequestTests {
		content := bytes.NewReader(make([]byte, 64))
		req := &http.Request{Header: http.Header{}}
		for k, v := range test.header {
			req.Header.Set(k, v)
		}
		_, _, err := EncryptRequest(content, req, "bucket", "object", test.metadata)
		if err != nil {
			t.Fatalf("Test %d: Failed to encrypt request: %v", i, err)
		}

        header.originalMessageSize = SMBUtil.readInt4(buffer, bufferIndex);
        bufferIndex += 4;

        // Skip reserved (2 bytes)
        bufferIndex += 2;

        // Read flags
        header.flags = SMBUtil.readInt2(buffer, bufferIndex);
        bufferIndex += 2;

        // Read session ID
        header.sessionId = SMBUtil.readInt8(buffer, bufferIndex);

        return header;
    }

func setEventStreamHeaders(w http.ResponseWriter) {
	w.Header().Set(xhttp.ContentType, "text/event-stream")
	w.Header().Set(xhttp.CacheControl, "no-cache") // nginx to turn off buffering
	w.Header().Set("X-Accel-Buffering", "no")      // nginx to turn off buffering
}

// Write http common headers
func setCommonHeaders(w http.ResponseWriter) {
	// Set the "Server" http header.
	w.Header().Set(xhttp.ServerInfo, MinioStoreName)

)

func getDefaultOpts(header http.Header, copySource bool, metadata map[string]string) (opts ObjectOptions, err error) {
	var clientKey [32]byte
	var sse encrypt.ServerSide

	opts = ObjectOptions{UserDefined: metadata}
	if v, ok := header[xhttp.MinIOSourceProxyRequest]; ok {
		opts.ProxyHeaderSet = true
		opts.ProxyRequest = strings.Join(v, "") == "true"
	}
	if _, ok := header[xhttp.MinIOSourceReplicationRequest]; ok {

			return xl.versions[i].header.ModTime > xl.versions[j].header.ModTime
		}) {
			t.Errorf("Contents not sorted")
		}
		for i := range xl.versions {
			hdr := xl.versions[i].header
			ver, err := xl.getIdx(i)
			if err != nil {
				t.Error(err)
				continue
			}
			gotHdr := ver.header()
			if hdr != gotHdr {
				t.Errorf("Header does not match, index: %+v != meta: %+v", hdr, gotHdr)

		req         *http.Request
		expectedErr error
	}{
		// Set valid authorization header.
		{
			req: &http.Request{
				Header: http.Header{
					"Authorization": []string{token},
				},
			},
			expectedErr: nil,
		},
		// No authorization header.
		{
			req: &http.Request{
				Header: http.Header{},
			},
			expectedErr: errNoAuthToken,
		},
		// Invalid authorization token.
		{

	req.Header.Set("content-md5", "====test")
	jsonReq := dumpRequest(req)
	type jsonResult struct {
		Method     string      `json:"method"`
		RequestURI string      `json:"reqURI"`
		Header     http.Header `json:"header"`
	}
	res := jsonResult{}